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Date:   Thu, 31 Oct 2019 15:15:38 +0200
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc:     mchehab@kernel.org, robh+dt@kernel.org, sakari.ailus@iki.fi,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        c.barrett@framos.com, a.brela@framos.com, peter.griffin@linaro.org
Subject: Re: [PATCH v4 1/2] dt-bindings: media: i2c: Add IMX296 CMOS sensor
 binding
Message-ID: <20191031131538.GA9170@pendragon.ideasonboard.com>
References: <20191030094902.32582-1-manivannan.sadhasivam@linaro.org>
 <20191030094902.32582-2-manivannan.sadhasivam@linaro.org>
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Hi Mani,

Thank you for the patch.

On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote:
> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also
> add MAINTAINERS entry for the binding and driver.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
>  .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++
>  MAINTAINERS                                   |  8 ++
>  2 files changed, 102 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml
> 
> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> new file mode 100644
> index 000000000000..c04ec2203268
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml
> @@ -0,0 +1,94 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor
> +
> +maintainers:
> +  - Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> +
> +description: |-
> +  The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image
> +  sensor with square pixel array and 1.58 M effective pixels. This chip
> +  features a global shutter with variable charge-integration time. It is
> +  programmable through I2C and 4-wire interfaces. The sensor output is
> +  available via CSI-2 serial data output (1 Lane).
> +
> +properties:
> +  compatible:
> +    const: sony,imx296
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +
> +  clock-names:
> +    description:
> +      Input clock for the sensor.
> +    items:
> +      - const: mclk

The pin is named INCK, let's name the clock accordingly.

> +  clock-frequency:
> +    description:
> +      Frequency of the mclk clock in Hertz.

This shouldn't be needed, you can retrieve the clock frequency at
runtime from the clock source.

> +  vddo-supply:
> +    description:
> +      Definition of the regulator used as interface power supply.
> +
> +  vdda-supply:
> +    description:
> +      Definition of the regulator used as analog power supply.
> +
> +  vddd-supply:
> +    description:
> +      Definition of the regulator used as digital power supply.

Do we really need three regulators ? I agree that the sensor has three
power rails, but aren't they usually powered by regulators that are
tied together, without individual control ? The IMX926 specifications
require the three power supplies to raise within 200ms, which we should
be able to ensure in software. What does your board use, does it have
multiple GPIOs to control each power supply ? If not I wonder if we
could just define vddd-supply now, and add vdda-supply and vddo-supply
later if we need to support systems that can control the supplies
individually.

> +  reset-gpios:
> +    description:
> +      The phandle and specifier for the GPIO that controls sensor reset.
> +    maxItems: 1
> +
> +  port: true
> +
> +required:
> +  - compatible
> +  - reg
> +  - clocks
> +  - clock-names
> +  - clock-frequency
> +  - vddo-supply
> +  - vdda-supply
> +  - vddd-supply
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    imx296: camera-sensor@1a {
> +        compatible = "sony,imx296";
> +        reg = <0x1a>;
> +        reset-gpios = <&msmgpio 35 GPIO_ACTIVE_LOW>;
> +        pinctrl-names = "default";
> +        pinctrl-0 = <&camera_rear_default>;
> +        clocks = <&gcc 90>;
> +        clock-names = "mclk";
> +        clock-frequency = <37125000>;
> +        vddo-supply = <&camera_vddo_1v8>;
> +        vdda-supply = <&camera_vdda_3v3>;
> +        vddd-supply = <&camera_vddd_1v2>;
> +
> +        port {
> +            imx296_ep: endpoint {
> +                remote-endpoint = <&csiphy0_ep>;
> +            };
> +        };
> +    };
> +
> +...
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 55199ef7fa74..51194bb2c392 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15140,6 +15140,14 @@ S:	Maintained
>  F:	drivers/media/i2c/imx274.c
>  F:	Documentation/devicetree/bindings/media/i2c/imx274.txt
>  
> +SONY IMX296 SENSOR DRIVER
> +M:	Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> +L:	linux-media@vger.kernel.org
> +T:	git git://linuxtv.org/media_tree.git
> +S:	Maintained
> +F:	drivers/media/i2c/imx296.c
> +F:	Documentation/devicetree/bindings/media/i2c/imx296.yaml
> +
>  SONY IMX319 SENSOR DRIVER
>  M:	Bingbu Cao <bingbu.cao@intel.com>
>  L:	linux-media@vger.kernel.org

-- 
Regards,

Laurent Pinchart